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The ongoing debate about whether cats or dogs are more intelligent may have finally been solved by scientists.

For the first time researchers have studied not just the size of animals’ brains, but the number of neurons in their cerebral cortex - the ‘little grey cells’ associated with thinking, planning and complex behavior which were revered by Hercule Poirot.

And the results show that although cats seem to adopt an air of intellectual superiority, they have just half the cortical neurons as the average golden retriever.

Dogs have about 530 million cortical neurons while cats have about 250 million. To put it in perspective, humans have around 16 billion.

“I believe the absolute number of neurons an animal has, especially in the cerebral cortex, determines the richness of their internal mental state and their ability to predict what is about to happen in their environment based on past experience,” said Dr Suzana Herculano-Houzel, Associate Professor of Psychology and Biological Sciences, of Vanderbilt University in Tennessee.

“I'm 100 percent a dog person, but, with that disclaimer, our findings mean to me that dogs have the biological capability of doing much more complex and flexible things with their lives than cats can.

“At the least, we now have some biology that people can factor into their discussions about who's smarter, cats or dogs."

Golden retrievers were even smarter with around 620 million neurons Credit:
Paul Mansfield photography

For the new study, the researchers analysed the brains of ferrets, mongoose, raccoons, cats, dogs, hyenas, lions and brown bears.

All belong to the order ‘carnivora’ which covers mammals that have teeth and claws which allows them to eat other creatures. The group was chosen because it has a large range of brain sizes, and include both domesticated and wild species.

They discovered that many animals with the largest brains have the lowest neurons.

For example the brain of a golden retriever has more neurons than a hyena, lion or brown bear, even though those animals have brains up to three times as large.

In fact, the study showed that a brown bear had a similar number of neurons to a cat, even though it has a brain which is 10 times as large, suggesting cats are as smart as bears, even if they are not as clever as dogs.

An illustration showing different brain sizes Credit:
Vanderbilt University

“One reason why dogs may have more neurons in their brains than cats may be because they are social animals,” she said,

“They are descended from wolves that hunt in a pack and therefore need a complex behaviours to co-operate with each other – behaviours like appeasement and reconciliation. This helps them co-operate with humans too, so we have guide dogs, medical detection dogs and so forth.

“Cats don’t have these behaviours because they hunt alone and can, and often do, live alone.

“Mind you, you could say that they are cleverer than dogs because they just eat cat food and don’t have to do anything in return. What’s so stupid about that?”

Dr Suzana Herculano-Houzel and her dog Credit:
Vanderbilt University

However The Kennel Club said that the majority of dog owners believe that their pets are smarter.

Caroline Kisko, Kennel Club Secretary, said: “There has always been a good natured rivalry between dog owners and cat owners and the majority of those who prefer dogs will likely say that they are intellectually superior to cats, so it’s interesting that this study seems to suggest that.

“These findings could well explain the fantastic versatility of dogs. Dogs thrive in many roles in society – from police and assistance dogs, to companion and search and rescue dogs – and they seem to have a biological ability to do much more than cats.”